Problem: If $x \dagger y = 3x-7$ and $x \triangleright y = x(y-3)$, find $-6 \dagger (1 \triangleright 5)$.
Solution: We don't need to find $1 \triangleright 5$ because $x \dagger y$ depends only on the left operand. Find $-6 \dagger y$ $ -6 \dagger y = (3)(-6)-7$ $ \hphantom{-6 \dagger y} = -25$.